Many animals, including humans, exhibit sets of behavioral traits that can be characterized along a "shy- bold" personality continuum. Behavioral traits such as willingness to explore new food sources, aggression in mate-acquisition, and latency to recover from stressful experiences are often correlated along the continuum. Shy-bold behavior can vary both within and among individuals in a population, and among populations. This variation can be under genetic control, but can also be significantly influenced by current environmental factors, age, or early developmental experience. The three-spine stickleback, Gasterosteus aculeatus, is a model system for both the study of behavior and evolutionary genomics, making it particularly suitable for examining the genetic and physiological processes that lead to variation in shy-bold personality types. Experiments will be used to determine how stickleback from different environments respond to stress (predator encounters). Stickleback from populations without predatory fish are expected to be bolder than stickleback from populations with predatory fish. Experiments with laboratory-reared stickleback will determine if genetic and/or endocrine differences explain natural variation in shy-bold behavior. [unreadable] [unreadable] [unreadable]